1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device and contactless electronic device having a function of rectifying a signal received by an antenna coil, and more particularly to a technology suitable for a rectifier in a semiconductor integrated circuit device.
2. Description of the Related Arts
The so-called contactless electronic device, which incorporates a semiconductor integrated circuit device and an antenna in a card, causes the semiconductor integrated circuit device to exchange information with an interrogator, and implements various functions, for instance, of transmitting data retained by the contactless electronic device and retaining data transmitted from the interrogator.
The semiconductor integrated circuit device incorporated in the contactless electronic device uses the antenna, which is incorporated in the contactless electronic device, to receive a high-frequency signal that is supplied from the interrogator, rectifies and smoothes a voltage generated across the antenna, and generates an internal voltage that is necessary for the operation of internal circuitry.
When the employed rectifying device is a MOS transistor whose gate and source are connected to antenna terminals, the MOS transistor parasitic capacitance, which is represented by gate-to-source capacitance, is applied between the antenna terminals. Therefore, the parasitic capacitance acts as a resonant capacitance that is connected in parallel with an antenna coil (refer to Japanese Patent Laid-open No. 8-97366 and JP-A-2002-514377).
Japanese Patent Laid-open No. 8-97366 describes a rectifier that does not forward bias a parasitic bipolar transistor and can remarkably reduce a leak current.
JP-A-2002-514377 describes a rectifier that can reduce a drain-to-source voltage at the time of conduction by making use of the substrate effect of a MOS transistor threshold voltage.
Japanese Patent Laid-open No. 2001-274339 describes a rectifier that reduces the rectifying-device-induced voltage loss by adding a series regulator function to a rectifier that comprises a MOS transistor.
Prior to this patent application, the inventors of the present invention studied problems that arise when a semiconductor integrated circuit device having a rectifier whose rectifying device comprises a MOS transistor described in Japanese Patent Laid-open No. 8-97366, JP-A-2002-514377, or Japanese Patent Laid-open No. 2001-274339 was applied to a contactless electronic device.